For the control of specific forms of circuit, e.g. transformers, multiphase motors etc. it is often necessary, if two or more pulse-width modulated activation signals are used, for these signals to have a specific waveform, in order to avoid such a transformer becoming saturated, and is thereby damaged or destroyed.
Previously such control signals have been produced by using two or more pulse-width modulated signals which must have the same switch-on time in consecutive time segments. In addition the other control output must be blanked in each second phase in each case.
This procedure is complex and time consuming however, and if a microcontroller is used for control, in some cases up to 80% of the resources of the microcontroller are used just for the production of symmetrical, pulse-width modulated control signals, so that only a few of the microcontroller's resources are available for other tasks.
For the control of multi-phase motors for example, such as 5-phase motors, which is possible with the signals mentioned at the start, high transition losses occur with the conventional method of changing the speed of the motor.